Method and apparatus for individually cooling components of electronic systems

ABSTRACT

A cooling system is configured to supply individually metered amounts of cooling fluid to heat generating components, e.g., processors, micro-controllers, high speed video cards, disk drives, semi-conductor devices, and the like, of an electronic system. The cooling system includes at least one variable speed fan, e.g., blower, configured to supply fluid through a centralized plenum and thereafter through a plurality of nozzles to the components of the electronic system. Each of the nozzles contains a valve to control the amount of fluid flow through the each of the nozzles. A controller is provided to control the operation of the variable speed fan and the operation of each of the valves is also controlled by a controller. By substantially controlling the amount of cooling fluid supplied to each of the components based upon the amount of heat generated by each component, the cooling system of the present invention may operate in a more efficient manner, thereby requiring substantially less energy than conventional cooling systems.

CROSS REFERENCE TO RELATED APPLICATION(S)

This is divisional of application Ser. No. 09/951,730 filed on Sep. 14,2001 now U.S. Pat. No. 6,904,968, which is hereby incorporated byreference herein.

FIELD OF THE INVENTION

This invention relates generally to electronic component coolingsystems. More particularly, the invention pertains to a cooling systemfor delivering jets of fluid in individually metered amounts tocomponents of a multi-component system.

BACKGROUND OF THE INVENTION

Some of the components (e.g., processors, micro-controllers, high speedvideo cards, disk drives, semi-conductor devices, and the like) of anelectronic system (e.g., computer system, entertainment system, and thelike) are known to generate relatively significant amounts of heat. Theheat generating components, along with other components of theelectronic system, are typically mounted on one or more printed circuit(PC) boards to thereby form a computer subsystem. Moreover, it isgenerally known that the performance and/or reliability of thecomponents typically deteriorate as the temperature of the componentsincrease. In an effort to improve the performance and/or reliability ofelectronic systems, they are typically equipped with a mechanism toprovide a cooling fluid, e.g., air, flow through a housing surroundingthe electronic systems to remove the generated heat. In these types ofelectronic systems, a fan or blower directs a tangential flow of coolingfluid across the PC board and heat sinks to cool the components byconvection.

Dissipating the heat generated by these components becomes ever moredifficult as the electronic systems incorporate greater numbers ofcomponents. By way of example, some high-end servers can house as manyas 64 microprocessors, with associated memory devices and ASICS,dissipating up to 20 kilowatts. Conventional cooling systems may beunable to adequately cool these types of electronic systems. Forinstance, the cooling fluid flow across a PC board may be relativelyimpeded by installation of the additional components blocking the fluidflow.

In addition, the tangential, unidirectional nature of the fluid flow asthe number of components increases as well as the number of thesubsystems, typically causes the multiple components to be cooled inseries. As a consequence, the cooling fluid flow may be a few degreeswarmer than expected, thus causing components located relativelydownstream to be cooled less than expected. This drawback may besomewhat alleviated by using a high fluid flow rate and by using heatsinks having a relatively large surface area. The large bulk volume flowcan also require the use of several blowers and relatively large exhaustducting. The resulting size and complexity of these types of coolingsystems have substantially detracted from their commercial viability,e.g., by adding additional costs to the overall electronic systems. Inaddition, the use of additional blowers generally increases the amountof energy and/or the space required to operate the cooling systems,thereby increasing the operating costs.

In addition, various components in electronic systems typically generatevarious amounts of heat and thus require various levels of cooling.Conventional cooling systems are typically operated in a substantiallyuniform manner, regardless of the level of heat generated by theindividual components. By way of example, conventional cooling systemsare generally designed to operate according to a worst-case scenario.That is, cooling fluid is supplied to the components at around 100% ofthe estimated cooling requirement. In one respect, conventional coolingsystems often attempt to cool components that may not be operating at alevel which may cause its temperature to exceed the predeterminedtemperature range. Consequently, conventional cooling systems oftenincur a greater amount of operating expense than is necessary tosufficiently cool the heat generating components.

SUMMARY OF THE INVENTION

According to one aspect, the present invention pertains to a system forcooling heat generating components. The system includes a variable speedblower and a plenum having an inlet and a plurality of outlets, whereinthe inlet of said plenum is in fluid communication with the blower. Thesystem also includes a plurality of tubes, each of the tubes having afirst end and a second end. The first ends of the tubes are connected tothe plurality of outlets of the plenum and the second ends of the tubesterminate at a location substantially close to at least one heatgenerating component. In addition, a valve is located along each of thetubes to independently vary a flow of the fluid through each of thetubes.

According to another aspect, the present invention pertains to a methodof efficiently cooling a plurality of heat generating components of anelectronic system having an enclosure and a plenum located within theenclosure. In the method, at least one variable speed blower and aplurality of valves are activated. Each of the valves terminatessubstantially close to a respective heat generating component, tothereby supply cooling fluid to the heat generating components. Thetemperatures of each of the heat generating components are each sensed.It is determined whether the sensed temperatures are within apredetermined temperature range. In addition, the supply of the coolingfluid to the heat generating components is varied in response to thesensed temperatures.

According to yet another aspect, the present invention relates to a racksystem for housing a plurality of heat generating components. The racksystem includes an enclosure having a plenum, the plenum including adivider separating the plenum into a first chamber and a second chamber.The second chamber includes a plurality of outlets for discharging thecooling fluid and the plenum extends generally along a side of theenclosure. The rack system also includes at least one variable speedblower configured to supply cooling fluid into the plenum and aplurality of nozzles that have a first end in fluid communication witheach of the plurality of outlets and a second end positionedsubstantially close to a respective one of the heat generatingcomponent. The rack system further includes a plurality of valves, eachof the valves being operable to vary the flow of the cooling fluidthrough each of the nozzles.

In comparison to known cooling mechanisms and techniques, certainembodiments of the invention are capable of achieving certain aspects,including some or all of the following: (1) substantially focalizedsupply of cooling fluid to individual heat generating components; (2)independent control of the fluid supply to the heat generatingcomponents; (3) energy efficient utilization of a plurality of blowersby operating them substantially only as needed; (4) substantial supplyof cooling fluid individually varied in accordance with actual oranticipated temperatures of the heat generating components. Thoseskilled in the art will appreciate these and other benefits of variousembodiments of the invention upon reading the following detaileddescription of a preferred embodiment with reference to the below-listeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present invention will become apparent tothose skilled in the art from the following description with referenceto the drawings, in which:

FIG. 1 shows a perspective view of a simplified illustration of anelectronic device, partly in section, in this instance a rack system,constructed in accordance with an embodiment of the present invention;

FIG. 2 shows a frontal plan view of the simplified illustration of theelectronic device illustrated in FIG. 1;

FIG. 3 shows a block diagram of a first exemplary control scheme for acooling system according to a first embodiment of the present invention;

FIG. 4 shows a block diagram of a second exemplary control scheme for acooling system according to a second embodiment of the presentinvention;

FIG. 5 shows a flow diagram of a first manner in which an embodiment ofthe present invention may be practiced; and

FIG. 6 shows a flow diagram of a second manner in which anotherembodiment of the present invention may be practiced.

DETAILED DESCRIPTION OF THE INVENTION

For simplicity and illustrative purposes, the principles of the presentinvention are described by referring mainly to an exemplary embodimentthereof. In the following description, numerous specific details are setforth in order to provide a thorough understanding of the presentinvention. It will be apparent however, to one of ordinary skill in theart, that the present invention may be practiced without limitation tothese specific details. In other instances, well known methods andstructure have not been described in detail so as not to unnecessarilyobscure the present invention.

According to a preferred embodiment of the present invention, a coolingsystem is configured to supply individually metered amounts of coolingfluid to heat generating components, e.g., processors,micro-controllers, high speed video cards, disk drives, semi-conductordevices, and the like, of an electronic system. Electronic systems mayinclude computer systems and entertainment systems, to name a few. Thecooling system includes at least one variable speed fan, e.g., blower,configured to supply cooling fluid, e.g., air, through a centralizedplenum and thereafter through a plurality of nozzles to the componentsof the electronic system. Each of the nozzles contains a valve tocontrol the amount of fluid flow through the each of the nozzles. Acontroller is provided to control the operation of the variable speedfan and the operation of each of the valves is also controlled by avalve controller. By substantially controlling the amount of coolingfluid supplied to each of the components based upon the amount of heatgenerated by each component, the cooling system of the present inventionmay operate in a more efficient manner, thereby requiring substantiallyless energy than conventional cooling systems.

FIG. 1 shows a perspective view of a simplified illustration of anelectronic device, partly in section, in this instance a rack system 10,constructed in accordance with an embodiment of the present invention,which may be used for housing a plurality of electronic components,e.g., subsystems, in an industrial, office, home or other environment.In addition, the present invention may be practiced in a variety ofelectronic devices. For instance, it is contemplated, although notlimited, that an embodiment of the present invention may be practiced inlarge and small scale rack systems, to name a few. For convenience,certain concepts of the present invention are depicted in theenvironment of the rack system 10 illustrated in FIG. 1.

While it is apparent that the parts of a rack system 10 may vary frommodel to model, the rack system includes an enclosure 12. The racksystem 10 also includes a plurality of blowers 14 operable to draw fluidfrom outside the enclosure 12 and deliver the fluid to the space withinthe enclosure. The blowers 14 are variable speed blowers because theyare configured to vary the amount of cooling fluid delivered to thecomponents within the rack system 10. Because the specific type ofblower to be used with the concepts of the invention may vary accordingto individual needs, the invention is not limited to any specific typeof blower and may thus utilize any reasonably suitable type of blowerthat is capable of accomplishing certain aspects of the invention. Inthis regard, the blowers 14 may comprise any reasonably suitable blowerthat is capable of varying the amount of fluid delivered to the spacewithin the enclosure. The choice of blower 14 may depend upon aplurality of factors, e.g., cooling requirements, costs, operatingexpenses, etc.

The number of blowers 14 implemented in accordance with an embodiment ofthe invention may vary according to individual needs. Accordingly, theinvention is not limited to any specific number of blowers and may thusutilize any reasonably suitable number of blowers that is capable ofaccomplishing certain aspects of the invention. According to a preferredembodiment of the present invention, at least two blowers 14 areimplemented to thereby enable a redundant fluid supply, in the eventthat one of the blowers malfunctions. In addition, a plurality ofblowers 14 may be provided to deliver fluid to both sides of theenclosure 12. In this respect, cooling fluid may be substantiallysimultaneously delivered through both sides of the enclosure 12.

The outlets of the blowers 14 are in fluid communication with a plenum16. The plenum 16 is in fluid communication with a plurality of nozzles18. The nozzles 18 have a first end and a second end, in which the firstend is connected to the plenum 16. The second ends of the nozzles 18 areconfigured to outlet fluid from the blowers 14 to one or more heatgenerating components 22 of a subsystem 20, as will be described ingreater detail hereinbelow with respect to FIG. 2. A subsystem 20 maycomprise a server. The cooling fluid supplied by the blowers 14, havingbeen relatively heated by the heat generating components 22, may beexpelled through an opening through the enclosure 12 as indicated byarrows 24. The rack system 10 may also include a plurality of powermodules 26 for supplying power to the components of the subsystems 20 aswell as the cooling system.

Referring now to FIG. 2, there is shown a frontal plan view of thesimplified illustration of the rack system 10 illustrated in FIG. 1. Asseen in FIG. 2, according to a preferred embodiment of the presentinvention, blowers 14 are situated to deliver cooling fluid to plena 16,30 located on both sides of the enclosure 12. Although not illustratedin FIG. 2, a plurality of blowers 14 may be provided to deliver coolingfluid to each of the plena 16, 30 for the purpose of providing aredundant cooling fluid supply to the heat generating components 22.According to an exemplary embodiment, the plena 16, 30 each extendsubstantially the entire width of the enclosure 12 such that a pluralityof blowers 14 may supply cooling fluid to each of the plena 16, 30.Alternatively, although not shown in FIG. 2, the plena 16, 30 maycomprise a plurality of separate passageways without deviating from thescope of the present invention.

The rack system 10 may also include a single plenum 16 along with anassociated one or more blower 14. In this instance, cooling fluid flowmay be delivered to the components through nozzles having variouslengths and extending from the single plenum 16. According to thisembodiment, the fluid flow entering into the enclosure 12 may bedirected into a single direction to thereby substantially preventcounteracting fluid flows within the enclosure. It is, however,envisioned that the present invention may operate with the two plena 16,30 configuration illustrated in FIG. 2. For example, a fan (not shown)may be incorporated into the rack system 10 to generally enable heatedfluid within the enclosure 12 to be expelled in the manner illustratedin FIG. 1. In this respect, the counteracting fluid flows from theplenums 16, 30 may be substantially obviated.

The rack system 10 is shown as including five subsystems 20 andassociated components 22, 48 for illustrative purposes only. Racksystems 10 have been known, however, to include upwards of forty (40) ormore subsystems 20. It may thus be seen that the greater the number ofsubsystems 20, and subsequent increase in the number of heat generatingcomponents 22, 48, the greater is the output required from each blower14 to cool the components. By substantially limiting the amount ofcooling fluid delivered to the heat generating components 22, 48, evenby a relatively small amount, the output required from each blower 14may be substantially reduced. The substantial reduction in the output ofthe blowers 14 generally equates to a reduction in the power consumed bythe blower, which, in turn equates to a savings in operating costs.

According to a preferred embodiment of the present invention, thecooling fluid flow through each of the nozzles 18 may be controlled toflow therethrough at relatively uniform velocities. One manner in whichthe fluid flow may be controlled is to ensure that the pressure of thefluid supplying each of the nozzles is substantially uniform. In thisrespect, each of the plena 16, 30 may include a respective divider 32,34. The width of the dividers 32, 34 may extend substantially along theentire width of each plenum 16, 30. The height of the dividers 32, 34may be slightly shorter than each of the plena 16, 30 to thus create agap 36 between a bottom edge of the dividers and a bottom inner surfaceof the plena. The dividers 32, 34 generally divide the space within theplena 16, 30 into two relatively separate chambers 38 a, 38 b. The firstchamber 38 a is in fluid communication with a baffle 40 connected to theblower 14. The second chamber 38 b is in fluid communication with thefirst chamber 38 b substantially only through the gap 36. In thisrespect, the cooling fluid flow originating from the blower 14 musttravel substantially the entire height of the plenum 30, i.e., throughthe first chamber 38 a, for the fluid flow to enter into the secondchamber 38 b.

The fluid in the second chamber 38 b may be maintained at asubstantially uniform static pressure by virtue of the manner in whichthe fluid is introduced into the second chamber 38 b. Fluid is suppliedinto the first chamber 38 a by the blower 14 at a relatively high ratethereby causing a relatively large amount of turbulence in the fluidlocated in the first chamber 38 a. Because of the distance the fluidmust travel to enter into the second chamber, by the time the fluidreaches the gap 36, the fluid has substantially stabilized, thusenabling the fluid entering into the second chamber 38 b to berelatively calm. In this respect, the fluid inside the second chamber 38b may be maintained at a relatively uniform pressure.

A plurality of nozzles 18 are in fluid communication with the secondchamber 38 b of the plenum 30 through attachment of respective firstends thereof to the second chamber 38 b. Each of the nozzles 18 includesa respective valve 42 to individually meter the flow of fluid to each ofthe components 22, 48. Each of the valves 42 may be electronicallycontrolled by a valve controller 44. A specific type of valve 42 is notrequired to be utilized with this exemplary embodiment of the presentinvention, but rather, any reasonably suitable type of controllablemetering valve may be utilized. An example of a suitable valve 42includes a valve operable to increase or decrease the amount of fluidflowing to a component. If the exemplary cooling system of the inventionemploys this type of valve 42, the valve controller 44 may be operableto vary the flow of fluid to the component at a wide range of flow ratesby controlling the size of the opening through which the fluid flowsthrough the nozzle 42. Another example of a suitable valve includes apulsating valve. In this type of valve 42, a constant diameter openingmay be covered by a lid that is operable to open and close the openingby pulsating. The flow rate of the fluid through the nozzle 42 may becontrolled by the valve controller 44 by varying the frequency ofpulsation. For instance, the frequency of pulsation may be increased todecrease the flow rate and the frequency may be decreased to increasethe flow rate.

Some of the heat generating components 22, e.g., microprocessors, whichgenerate relatively significant amounts of heat, are illustrated ascomprising heat sinks 46 attached to upper surfaces thereof. Othercomponents 48, e.g., memory devices and ASICS, which generate lesseramounts of heat but nevertheless still require supplemental cooling arenot illustrated as having heat sinks. The heat sinks 46 may be attachedto the heat generating components 22, for example, by soldering, epoxy,thermal compound, and the like). Alternatively, the heat sinks 46 may bemechanically clamped to the heat generating components 22. A specifictype of heat sink is not required to be utilized with the cooling systemof the present invention, but rather, any suitable type of heat sink maybe employed. For example, one skilled in the art would readily recognizethat a plurality of variously configured heat sinks may be employed withthe exemplary embodiment of the present invention without deviating fromthe scope thereof.

In any event, the second ends of some of the nozzles 18 locatedgenerally away from the plena 16, 30 terminate at a substantially closedistance to each of the components 22 and 48. Alternatively, some of thecomponents 48 may be positioned generally behind a heat generatingcomponent 22 to thereby receive supplemental fluid flow directed at theheat generating component 22. The distance between the second ends andthe heat sinks 46 and/or the components 48 may be determined based upontesting to optimize the heat transfer from the heat sinks and/or thecomponents into the cooling fluid. In one respect, the distance may beset such that the impinging zone of the fluid flow is substantiallydirectly located within the area of the heat sinks 46 and/or thecomponents 48 to thereby increase the potential for maximum heattransfer. Because the fluid from the nozzles 18 generally flows into thefluid located substantially adjacent to the components 22, 48, the flowis considered as being submerged. The fluid flow from the nozzles 18thus mixes with the adjacent fluid, thereby causing the fluid flow toexpand. The mixing of the fluid causes the flow rate of the fluid fromthe nozzles 18 to generally increase, however, the maximum velocity ofthe fluid from the nozzles generally decreases. There is thus arelatively optimum distance where the second ends of the nozzles 18 maybe positioned with respect to the components 22, 48 to maximize bothflow rate and velocity of the fluid from the nozzles.

According to an exemplary embodiment, each subsystem 20 of the racksystem 10 may include at least one valve controller 44. As describedhereinabove, the valve controller 44 is operable to manipulate thevalves 42 to thereby control the flow of fluid through each of thenozzles 18. The valve controller 44 may manipulate the valves 42 basedupon the actual temperature of each of the heat generating components22, 48 or through an anticipated temperature of each of the components.The actual temperature of the heat generating components 22, 48 may bedetermined by a temperature sensor (not shown), e.g., thermocouple,located on the heat generating component 22, 48 or the heat sink 46. Forexample, the temperature sensor may be integrally formed with the heatgenerating component 22, 48, the heat sink 46, or the temperature sensormay be attached on the heat generating component or the heat sink. Theanticipated temperature of the heat generating components 22, 48 may bepredicated upon an impending load on the heat generating component. Forexample, the valve controller 44 may be connected to another controller,e.g., a central controller for the subsystems, which anticipates theheat load the components 22, 48 will dissipate. This information may berelayed to the valve controller 44 which may then manipulate the valve42 according to the anticipated load.

In any event, if there is an actual change or an anticipated change inthe temperature of the respective heat generating components 22, 48, thevalve controller 44 generally operates to manipulate the correspondingvalve 42 to compensate, i.e., changes the flow rate of the coolingfluid, for the change in temperature. In this respect, each of thecomponents 22, 48 generally receives substantially only the amount ofcooling fluid necessary to maintain the temperature of the components22, 48 within a predetermined temperature range. As will be seen fromthe discussion hereinbelow, by controlling the cooling fluid flow inthis manner, the blowers 14 may be operated at a substantially optimizedlevel, thereby decreasing the amount of energy and thus the operatingcosts required to operate the blowers 14.

The amount of cooling fluid the blowers 14 deliver to the plena 16, 30is controlled by one or more blower controllers 50. The blowercontrollers 50 may control the speed, and thus the fluid intake, of theblowers 14 in a variety of different manners. By way of example, theblower controllers 50 may control the speed of the blowers 14 byadjusting the amount of power supplied to the blowers. Alternatively,the blower controllers 14 may adjust the speed of the blowers 14 in anymanner generally known to those skilled in the art. In any respect, theblower controllers 50 may operate to manipulate the blowers 14 inresponse to a variety of factors. By way of example, the speed of theblowers 14 may be manipulated, e.g., either increased or decreased, inresponse to manipulation of the valves 42, e.g., to increase or decreasethe flow rate of the cooling fluid. In this instance, the blowercontrollers 50 may be connected either directly or indirectly to thevalve controllers 44 such that any manipulation of the valves 42 will beautomatically detected by the blower controllers to thereby adjust thespeed of the blowers 14.

As another example, the blower controllers 50 may operate to manipulatethe speed of the blowers 14 in response to changes in pressure withinthe plena 16, 30. In this instance, a pressure sensor 52 may be situatedeither at one location or at various locations within the plena 16, 30.The measurements obtained by the pressure sensor 52 may be relayed tothe blower controllers 50. The blower controllers 50 may detect anydiscernable change in the pressure of the fluid located within the plena16, 30 and alter the blower speed accordingly. For example, if thepressure sensor 52 measures a change in the pressure, or alternatively,if the pressure sensor detects a predetermined degree of pressurechange, the blower controllers 50 may control the blowers 14 to altertheir speeds. In this respect, the amount of energy expended to supplythe heat generating components 22, 48 with cooling fluid issubstantially optimized. Therefore, only that amount of energy requiredto substantially cool the heat generating components 22, 48 is expended,which correlates to a substantial energy savings over known coolingsystems.

FIG. 3 shows a block diagram 300 of a first exemplary control scheme fora cooling system 302 according to a first embodiment of the presentinvention. The following description of the block diagram 300illustrates one manner in which the cooling system 302 maybe operated inaccordance with a first embodiment of the present invention. In thisrespect, it is to be understood that the following description of theblock diagram 300 is but one manner of a variety of different manners inwhich such a cooling system 302 may be operated.

The valve controller 304 is configured to receive the measuredtemperatures of a plurality of heat generating components, e.g., heatgenerating components 22, 48. In this regard, the controller 304 maycomprise a microprocessor, a micro-controller, an application specificintegrated circuit, ASIC and the like. The temperatures of the heatgenerating components may be measured by temperature sensors 306 and308. Although FIG. 3 illustrates two temperature sensors 306 and 308, itshould be understood that the number of temperature sensors is notcritical to the operation of the first embodiment of the invention.Instead, the cooling system 302 may include any reasonably suitablenumber of temperature sensors to thus measure the temperatures of anyreasonably suitable number of heat generating components. According to apreferred embodiment, the number of temperature sensors and thus thetemperature measurements of the number of heat generating components maybe upgradable, e.g., scalable, to include any additional heat generatingcomponents that may be included in a rack system, for example.

The temperature sensors 306 and 308 may be integrally formed with theheat generating component and/or heat sink. Alternatively, thetemperature sensors 306 and 308 may be attached to the heat generatingcomponents and/or the heat sinks by any suitable means known to those ofskill in the art. In any event, the temperatures measured by thetemperature sensors 306 and 308 for the individual heat generatingcomponents are relayed to the valve controller 304.

As an alternative to the temperature sensors 306 and 308, the valvecontroller 304 may be configured to anticipate the temperatures of theheat generating components. The anticipated temperatures of the heatgenerating components may be predicated upon impending loads on the heatgenerating components. For example, the valve controller 304 may beconnected to another controller (not shown), e.g., a central controllerfor the subsystem, which anticipates the heat load the components willdissipate. This information may be relayed to the valve controller 304which may then manipulate the valves 310 and 312 according to theanticipated loads.

The valve controller 304 is additionally configured to control valves310 and 312. Interface electronics 318 may be configured to provide aninterface between the valve controller 304 and the components foroperating the control valves 310 and 312, e.g., a motor to control theopening in the valves, device for operating the pulsating valve (notshown), etc. As stated hereinabove, the valves 310 and 312 may compriseany reasonably suitable type of valve capable of altering the flow offluid therethrough, e.g., pulsating valve.

Although FIG. 3 illustrates two valves 310 and 312, it should beunderstood that the number of valves is not critical to the operation ofthe first embodiment of the invention. Instead, the cooling system 302may include any reasonably suitable number of valves 310 and 312 to thuscontrol the flow of cooling fluid delivered to any reasonably suitablenumber of heat generating components. According to a preferredembodiment, the number of valves 310 and 312 and thus the number of heatgenerating components may be upgradable, e.g., scalable, such that thevalve controller 304 may operate to control the flow of cooling fluid tosubsequently added heat generating components.

The valve controller 304 may be configured to manipulate the valves 310and 312 independently of one another. In this respect, the valvecontroller 304 may control the valve 310 to increase the flow of fluidtherethrough in response to an increase in temperature of acorresponding heat generating component while maintaining a relativelyuniform flow of fluid through the valve 312. Consequently, each of theheat generating components may receive substantially only that amount ofcooling generally necessary to maintain the respective heat generatingcomponents within a predetermined temperature range.

The controller 304 is further configured to relay information signals toa blower controller 314 which controls the operation of a plurality ofblowers 316. Interface electronics 320 may be configured to provide aninterface between the blower controller 314 and the components foroperating the blowers 316, e.g., voltage supply to the blowers,mechanism to control the speed of the blowers (not shown), etc. Thenumber of blowers 316 is not critical to the operation of the firstembodiment of the invention. Instead, the cooling system 302 may includeany reasonably suitable number of blowers 316 to deliver cooling fluidto the heat generating components. According to an exemplary embodiment,a plurality of blowers 316 are employed in the cooling system 302, witheach of the blowers 316 configured to supply cooling fluid to commonplena, to thereby create a redundant fluid intake system. The blowercontroller 314 may operate the blowers 316, e.g., vary the speeds of theblowers, in response to the manipulation of the valves 310 and 312 bythe valve controller 304.

FIG. 4 shows a block diagram 400 of a second exemplary control schemefor a cooling system 402 according to a second embodiment of the presentinvention. The elements illustrated in the block diagram 400 operate insubstantially the same manner as those elements illustrated in the blockdiagram 300, except that the blower controller 414 is configured tooperate independently of the valve controller 404. For example, thevalve controller 404 operates in substantially the same manner as thevalve controller 302. In this respect, only those elements in the blockdiagram 400 that differ from those elements in the block diagram 300will be described hereinbelow. In this respect, interface electronics420 may be configured to provide an interface between the valvecontroller 404 and the components for operating the control valves 410and 412, e.g., a motor to control the opening in the valves, device foroperating the pulsating valve (not shown), etc. In addition, interfaceelectronics 422 may be configured to provide an interface between theblower controller 414 and the components for operating the blowers 416,e.g., voltage supply to the blowers, mechanism to control the speed ofthe blowers (not shown), etc.

A pressure sensor 418 is configured to measure the pressure within theplena of an electronic system, e.g., rack system 10. The pressuremeasurements obtained by the pressure sensor 418 is relayed to theblower controller 414. In response to changes in the measured pressure,the blower controller 414 manipulates the speed of the blowers 416 tovary the amount of cooling fluid supplied to a plurality of heatgenerating components. In this respect, the blowers 416 operate togenerally maintain the fluid pressure within the plena at asubstantially uniform level. Thus, the blower controller 414 is operableto increase the speed of the blowers 416, e.g., expend a greater amountof energy, substantially as the heat generated by the heat generatingcomponents requires such an increase. Consequently, the blowers 416 arenot operated at a substantially constant energy level and the amount ofenergy necessary is substantially lower than that of conventionalcooling systems that typically operate at maximum energy levels.

FIG. 5 shows a flow diagram 500 of a first manner in which an embodimentof the present invention may be practiced. The following description ofthe flow diagram 500 is made with reference to the block diagram 300illustrated in FIG. 3, and thus makes reference to the elements citedtherein. It is to be understood that the steps illustrated in the flowdiagram 500 may be contained as a utility, program, subprogram, in anydesired computer accessible medium. In addition, the flow diagram 500may be embodied by a computer program, which can exist in a variety offorms both active and inactive. For example, they can exist as softwareprogram(s) comprised of program instructions in source code, objectcode, executable code or other formats. Any of the above can be embodiedon a computer readable medium, which include storage devices andsignals, in compressed or uncompressed form.

Exemplary computer readable storage devices include conventionalcomputer system RAM (random access memory), ROM (read only memory),EPROM (erasable, programmable ROM), EEPROM (electrically erasable,programmable ROM), and magnetic or optical disks or tapes. Exemplarycomputer readable signals, whether modulated using a carrier or not, aresignals that a computer system hosting or running the computer programcan be configured to access, including signals downloaded through theInternet or other networks. Concrete examples of the foregoing includedistribution of the programs on a CD ROM or via Internet download. In asense, the Internet itself, as an abstract entity, is a computerreadable medium. The same is true of computer networks in general. It istherefore to be understood that those functions enumerated below may beperformed by any electronic device capable of executing theabove-described functions.

In the flow diagram 500, a plurality of blowers 316 are activated andthe valves 310 and 312 are opened at step 502. At step 504, thetemperatures of the components (Tc's) are individually sensed by thetemperature sensors 306 and 308. Alternatively, the Tc's may beanticipated in the manner described hereinabove with respect to FIG. 3.At step 506, it is determined whether each of the measured temperaturesare individually within a predetermined range of operating temperatures,e.g., between a maximum set point temperature (Tmax,set) and a minimumset point temperature (Tmin,set). The predetermined range of operatingtemperatures may be set according to a plurality of factors. Thesefactors may include, for example, the operating temperatures set forthby the manufacturers of the heat generating components, through testingto determine the optimal operating temperatures, etc. In addition, thepredetermined range of operating temperatures may vary from one heatgenerating component on the basis that various components generally mayoperate effectively at various temperatures.

The temperatures for those heat generating components determined to havetemperatures that fall within the predetermined range, are sensed againat step 504. For those heat generating components determined to havetemperatures that do not fall within the predetermined temperaturerange, i.e., fall outside of Tmin,set and Tmax,set, it is determinedwhether the sensed temperature equals or falls below the Tmin,set atstep 508. In general, the range of temperatures Tmin,set and Tmax,setpertains to threshold temperatures to determine whether to increase ordecrease the flow of cooling fluid delivered to the individual heatgenerating components. The predetermined temperature range may be basedupon a plurality of factors, for example, a threshold operating range oftemperatures that may be determined through testing to substantiallyoptimize the performance of the heat generating components. Moreover,the predetermined temperature range may vary for each heat generatingcomponent because various components generally may operate effectivelyat various temperatures and thus various threshold temperatures may berequired.

If the Tc's of some of the heat generating components are below or equalto the Tmin,set, the valve controller 304 may operate to decrease theflow of cooling fluid to those heat generating components at step 510.If the Tc's of some of the heat generating components exceed theTmin,set (i.e., also exceeds the Tmax,set), the valve controller 304 mayoperate to increase the flow of cooling fluid to those heat generatingcomponents at step 512.

The decrease of cooling fluid flow at step 510 and the increase ofcooling fluid flow at step 512 may be accomplished by incrementallyvarying the fluid flow through the valves. An example will be made forthe instance where a valve allows a certain amount of fluid to flowtherethrough, and the valve is manipulated to decrease the fluid flow,and where the decrease in fluid flow is insufficient to cause the Tc forthat component to fall within the predetermined range. In this instance,during a subsequent run through steps 504–510, the valve will becontrolled to further decrease the fluid flow therethrough by anincremental amount. By repeating this process a number of times, thetemperature of the component may be substantially brought within thepredetermined range.

At step 514, the blower controller 314 may determine whether to decreasethe blower speed. The determination of whether to decrease the blowerspeed may be made in response to the manipulations made to the valves bythe valve controller 304. For instance, if the total amount of decreasein the flow of cooling fluid exceeds the total amount of increase in theflow of cooling fluid, the blower controller 314 may operate to decreasethe speed of the blowers at step 516. Alternatively, if the total amountof increases in the flow of cooling fluid exceeds the total amount ofdecreases, the blower controller 314 may operate to increase the blowerspeed at step 518.

Following steps 516 and/or 518, or if the increases in the flow ofcooling fluid through the nozzles equals the decreases, the temperaturesof the components are sensed again at step 504. In addition, the stepsfollowing step 504 may be repeated for an indefinite period of time solong as the cooling system 302 is in operation.

It should be appreciated that the Tc's of some of the heat generatingcomponents may fall below the Tmin,set, whereas the Tc's of other onesof the heat generating components may exceed the Tmax,set. Thus, itshould be appreciated that steps 510 and 512 may be respectively andsubstantially simultaneously performed on the various heat generatingcomponents.

FIG. 6 shows a flow diagram 600 of a second manner in which anotherembodiment of the present invention may be practiced. The followingdescription of the flow diagram 600 is made with reference to the blockdiagram 400 illustrated in FIG. 4, and thus makes reference to theelements cited therein. It is to be understood that the stepsillustrated in the flow diagram 600 may be contained as a utility,program, subprogram, in any desired computer accessible medium. Inaddition, the flow diagram 600 may be embodied by a computer program,which can exist in a variety of forms both active and inactive. Forexample, they can exist as software program(s) comprised of programinstructions in source code, object code, executable code or otherformats. Any of the above can be embodied on a computer readable medium,which include storage devices and signals, in compressed or uncompressedform.

Exemplary computer readable storage devices include conventionalcomputer system RAM (random access memory), ROM (read only memory),EPROM (erasable, programmable ROM), EEPROM (electrically erasable,programmable ROM), and magnetic or optical disks or tapes. Exemplarycomputer readable signals, whether modulated using a carrier or not, aresignals that a computer system hosting or running the computer programcan be configured to access, including signals downloaded through theInternet or other networks. Concrete examples of the foregoing includedistribution of the programs on a CD ROM or via Internet download. In asense, the Internet itself, as an abstract entity, is a computerreadable medium. The same is true of computer networks in general. It istherefore to be understood that those functions enumerated below may beperformed by any electronic device capable of executing theabove-described functions.

In the flow diagram 600, a plurality of blowers 416 are activated andthe valves 410 and 412 are opened at step 602. At step 604, thetemperatures of the components (Tc's) are individually sensed by thetemperature sensors 406 and 408. Alternatively, the Tc's may beanticipated in the manner described hereinabove with respect to FIG. 3.At step 606, it is determined whether each of the measured temperaturesare individually within a predetermined range of operating temperatures.The predetermined range of operating temperatures may be set accordingto a plurality of factors. These factors may include, for example, theoperating temperatures set forth by the manufacturers of the heatgenerating components, through testing to determine the optimaloperating temperatures, etc. In addition, the predetermined range ofoperating temperatures may vary from one heat generating component onthe basis that various components generally may operate effectively atvarious temperatures.

The temperatures for those heat generating components determined to havetemperatures that fall within the predetermined temperature range, e.g.,between a predetermined minimum set point temperature (Tmin,set) and apredetermined maximum set point temperature (Tmax,set), and are sensedagain at step 604. For those heat generating components determined tohave temperatures that do not fall within the predetermined temperaturerange, it is determined whether the sensed temperature falls below theTmin,set at step 608. In general, the predetermined temperature rangepertains to threshold temperatures to determine whether to increase ordecrease the flow of cooling fluid delivered to the individual heatgenerating components. The predetermined temperature range may be basedupon a plurality of factors, for example, a threshold operatingtemperature or range of temperatures that may be determined throughtesting to substantially optimize the performance of the heat generatingcomponents. The predetermined temperature range may vary for each heatgenerating component because various components generally may operateeffectively at various temperatures and thus various thresholdtemperatures may be required.

If the Tc's of some of the heat generating components are below or equalto the Tmin,set, the valve controller 404 may operate to decrease theflow of cooling fluid to those heat generating components at step 610.If the Tc's of some of the heat generating components exceed theTmin,set (i.e., exceed the Tmax,set), the valve controller 404 mayoperate to increase the flow of cooling fluid to those heat generatingcomponents at step 612.

The decrease of cooling fluid flow at step 610 and the increase ofcooling fluid flow at step 612 may be accomplished by incrementallyvarying the fluid flow through the valves. An example will be made forthe instance where a valve allows a certain amount of fluid to flowtherethrough, and the valve is manipulated to decrease the fluid flow,and where the decrease in fluid flow is insufficient to cause the Tc forthat component to fall within the predetermined range. In this instance,during a subsequent run through steps 604–610, the valve will becontrolled to further decrease the fluid flow therethrough by anincremental amount. By repeating this process a number of times, thetemperature of the component may be substantially brought within thepredetermined range.

At step 614, the pressure of the cooling fluid located in the plena maybe measured by a pressure sensor 418. The measured pressure may berelayed to the blower controller 414. The blower controller 414 maydetermine whether the measured pressure is within a predeterminedpressure range, e.g., a predetermined minimum set point pressure(Pmin,set) and a predetermined maximum set point pressure (Pmax,set), atstep 616. The predetermined pressure range may be set according to adesired velocity of the cooling fluid to be ejected through the nozzles.In addition, the predetermined pressure range may be the substantialoptimum operating pressure desired for controlling the flow of coolingfluid through the nozzles. If the measured pressure is within thepredetermined pressure range, the steps beginning with step 604 may befollowed again.

If the measured pressure is not within the predetermined pressure range,it is determined whether the measured pressure (P) is below or equal toa minimum pressure set point (Pmin,set) at step 618. In general, thepredetermined pressure range pertains to the threshold pressures todetermine whether to increase or decrease the supply of fluid into theplena. The predetermined pressure range may be based upon a plurality offactors, for example, a threshold operating pressure or range ofpressures that may be determined through testing to substantiallyoptimize the performance of the cooling fluid output through thenozzles.

If the P is determined to be below or equal to the Pmin,set, the blowercontroller 414 may operate to increase the blower speed, e.g., byincreasing the voltage flow to the blower, at step 620. Alternatively,if the P is determined to exceed the Pmin,set, and thereby exceed thePmax,set, the blower controller 414 may operate to decrease to theblower speed at step 622.

Following steps 620 and/or 622, the temperatures of the components aresensed again at step 604. In addition, the steps following step 604 maybe repeated for an indefinite period of time so long as the coolingsystem 402 is in operation.

It should be appreciated that the Tc's of some of the heat generatingcomponents may fall below the Tmin,set, whereas the Tc's of other onesof the heat generating components may exceed the Tmax,set. Thus, steps610 and 612 may be respectively and substantially simultaneouslyperformed on the various heat generating components.

By virtue of certain aspects of the present invention, the amount ofenergy, and thus the costs associated with cooling heat generatingcomponents of an electronic system, may be substantially reduced. In onerespect, by operating the blowers of a cooling system to supply coolingfluid substantially only as needed by the heat generating components,the cooling system may be operated at a relatively more efficient manneras compared to conventional cooling systems.

What has been described and illustrated herein is a preferred embodimentof the invention along with some of its variations. The terms,descriptions and figures used herein are set forth by way ofillustration only and are not meant as limitations. Those skilled in theart will recognize that many variations are possible within the spiritand scope of the invention, which is intended to be defined by thefollowing claims—and their equivalents—in which all terms are meant intheir broadest reasonable sense unless otherwise indicated.

1. A method of cooling a plurality of heat generating components of anelectronic system having an enclosure and a plenum located within saidenclosure, said method comprising: activating at least one variablespeed blower and a plurality of valves, each of said valves terminatingsubstantially close to a respective heat generating component, tothereby supply cooling fluid to said heat generating components; sensingthe temperatures of each of said heat generating components; determiningwhether said sensed temperatures are within a predetermined temperaturerange; varying said supply of said cooling fluid to said heat generatingcomponents in response to said sensed temperatures falling outside ofsaid predetermined temperature range sensing a pressure of a supply ofsaid cooling fluid; determining whether said sensed pressure is within apredetermined pressure range; and varying said speed of said at leastone blower in response to said sensed pressure falling outside of saidpredetermined pressure range.
 2. The method according to claim 1,further comprising: determining whether the measured temperatures ofsaid heat generating components are each below or equal to apredetermined minimum set point temperature.
 3. The method according toclaim 2, further comprising: decreasing the supply of said cooling fluidto said heat generating components for those heat generating componentshaving measured temperatures that fall below or equal said predeterminedminimum set point temperature.
 4. The method according to claim 3,further comprising: decreasing the speed of said at least one blower inresponse to said decreasing cooling fluid supply to said heat generatingcomponents exceeding said increasing cooling fluid supply to said heatgenerating components.
 5. The method according to claim 2, furthercomprising: increasing the supply of said cooling fluid to said heatgenerating components for those heat generating components havingmeasured temperatures that exceed said predetermined minimum set pointtemperature.
 6. The method according to claim 5, further comprising:increasing the speed of said at least one blower in response to saiddecreasing cooling fluid supply to said heat generating componentsfalling below said increasing cooling fluid supply to said heatgenerating components.
 7. The method according to claim 1, wherein saidstep of varying said blower speed comprises determining whether saidmeasured pressure falls below or equals a predetermined minimum setpoint pressure range.
 8. The method according to claim 7, furthercomprising: increasing the speed of said at least one blower in responseto said measured pressure falling below or equaling said predeterminedminimum set point pressure.
 9. The method according to claim 7, furthercomprising: decreasing the speed of said at least one blower in responseto said measured pressure exceeding said predetermined minimum set pointpressure.
 10. The method according to claim 1, further comprising:supplying the plenum with cooling fluid with the at least one variablespeed blower prior to supplying the cooling fluid to said heatgenerating components; and substantially maintaining a portion of thecooling fluid at a substantially uniform pressure.
 11. The methodaccording to claim 1, wherein the step of sensing the temperatures ofeach of said heat generating components comprises detecting thetemperatures with one or more temperature sensors.
 12. The methodaccording to claim 1, wherein the step of sensing the temperatures ofeach of said heat generating components comprises anticipating thetemperatures of each of said heat generating components based upon animpending load on each of the heat generating components.
 13. A computerreadable storage medium on which is embedded one or more computerprograms, said one or more computer programs implementing a method forcooling a plurality of heat generating components of an electronicsystem having an enclosure and a plenum located within said enclosure,said one or more computer programs comprising a set of instructions for:activating at least one variable speed blower and a plurality of valves,each of said valves terminating substantially close to a respective heatgenerating component, to thereby supply cooling fluid to said heatgenerating components; sensing the temperatures of each of said heatgenerating components; determining whether said sensed temperatures arewithin a predetermined temperature range; varying said supply of saidcooling fluid to said heat generating components in response to saidsensed temperatures falling outside of said predetermined temperaturerange sensing a pressure of a supply of said cooling fluid; determiningwhether said sensed pressure is within a predetermined pressure range;and varying said speed of said at least one blower in response to saidsensed pressure falling outside of said predetermined pressure range.14. The computer readable storage medium according to claim 13, said oneor more computer programs further comprising a set of instructions for:determining whether the measured temperatures of said heat generatingcomponents are each below or equal to a predetermined minimum set pointtemperature.
 15. The computer readable storage medium according to claim14, said one or more computer programs further comprising a set ofinstructions for: decreasing the supply of said cooling fluid to saidheat generating components for those heat generating components havingmeasured temperatures that fall below or equal said predeterminedminimum set point temperature.
 16. The computer readable storage mediumaccording to claim 14, said one or more computer programs furthercomprising a set of instructions for: increasing the supply of saidcooling fluid to said heat generating components for those heatgenerating components having measured temperatures that exceed saidpredetermined minimum set point temperature.
 17. The computer readablestorage medium according to claim 13, said one or more computer programsfurther comprising a set of instructions for: supplying the plenum withcooling fluid with the at least one variable speed blower prior tosupplying the cooling fluid to said heat generating components; andsubstantially maintaining a portion of the cooling fluid at asubstantially uniform pressure.
 18. The computer readable storage mediumaccording to claim 13, said one or more computer programs furthercomprising a set of instructions for: anticipating the temperatures ofeach of said heat generating components based upon an impending load oneach of the heat generating components.
 19. The computer readablestorage medium according to claim 13, said one or more computer programsfurther comprising a set of instructions for: determining whether saidmeasured pressure falls below or equals a predetermined minimum setpoint pressure range.
 20. The computer readable storage medium accordingto claim 19, said one or more computer programs further comprising a setof instructions for: increasing the speed of said at least one blower inresponse to said measured pressure falling below or equaling saidpredetermined minimum set point pressure.
 21. The computer readablestorage medium according to claim 19, said one or more computer programsfurther comprising a set of instructions for: decreasing the speed ofsaid at least one blower in response to said measured pressure exceedingsaid predetermined minimum set point pressure.